Soybean (Glycine max L. Merr) is a major cash crop and investment commodity in North America and elsewhere. Soybean oil is one of the most widely used edible oils, and soybeans are used worldwide both in animal feed and in human food production. Most soybean cultivars can be classified into two categories of stem termination, commonly known as indeterminate and determinate types. In indeterminate cultivars, the apical meristems at the stem and branch apices maintain vegetative activity until photosynthate demand by developing seeds causes a cessation in the production of vegetative dry matter. In contrast, the apical meristems in determinate cultivars cease vegetative activity at or soon after photoperiod-induced floral induction, and then the meristems become reproductive inflorescences. It is known that stem termination has great effects on plant height, flowering period, node production, maturity, water-use efficiency, and soybean yield. Usually the indeterminate cultivars are more widely adapted and more stable to adverse environmental conditions. Therefore the use of SNP markers is very important for soybean germplasm assessment and to set up breeding yield testing trials according to determinate or indeterminate stem growth habit. In the present invention we have detected strong associations with the Dt1 locus that control stem termination in soybean thus allowing a plant breeder to quickly and efficiently select determinate or the favorable indeterminate soybean plant.
Until now stem termination has primarily been assessed through phenotyping, which can be time consuming and can only be done at late stages of breeding programs, due to its low throughput. This invention describes the discovery of a QTL region in the soybean genome that is associated with stem termination (specifically being able to assess whether a line will be determinate (an unfavorable phenotype) or indeterminate (a favorable phenotype). The ultimate benefit of this invention is to select favorable soybean phenotypes not having detrimental traits associated with stem termination based on SNP markers at early breeding stages and support the breeding pipeline by filling it in with lines enriched for the alleles not giving rise to negative phenotypes associated with stem termination.
SNP markers associated with stem termination in soybean will support selections by the soybean breeding programs on earlier breeding stages and will assure that only plants with desirable alleles will be advanced to late stage testing. Also, there is an expected improvement of cost efficiency by eliminating the need of expensive low throughput phenotyping at early breeding stages, thus increasing accuracy of the selection and maximizing the value of investments in field testing. From a trait introgression perspective, the SNP marker can be deployed for rapid introgression of both GM and native traits; expansion of allele frequency for native traits in a broad germplasm base.